.nested-list-container {
  padding: 20px;
  background-color: var(--background-color);
  min-height: calc(100vh - 50px);
}

.description {
  margin-bottom: 20px;
}

.statistics-panel {
  margin-bottom: 20px;
}

.stat-card {
  background: rgba(255, 255, 255, 0.95);
  border-radius: 12px;
  padding: 15px 20px;
  display: flex;
  align-items: center;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.05);
  border: 1px solid var(--border-color-light);
  transition: all 0.3s ease;
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.08);
}

.stat-icon {
  width: 50px;
  height: 50px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: white;
  margin-right: 15px;
}

.stat-icon.categories { background: linear-gradient(135deg, #409EFF, #337ECC); }
.stat-icon.levels { background: linear-gradient(135deg, #E6A23C, #CC8E33); }
.stat-icon.books { background: linear-gradient(135deg, #67C23A, #5CB85C); }
.stat-icon.strategy { background: linear-gradient(135deg, #909399, #70747B); }

.stat-info h3 {
  margin: 0 0 5px 0;
  font-size: 1.5rem;
  font-weight: bold;
  color: var(--text-color);
}

.stat-info p {
  margin: 0;
  color: var(--text-color-secondary);
  font-size: 0.85rem;
}

.control-panel {
  margin-bottom: 20px;
  background: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.control-form .el-form-item {
  margin-bottom: 0;
  margin-right: 15px;
}

.control-form .el-button {
  margin-bottom: 10px;
}

.tree-container {
  background: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  min-height: 300px;
}

.tree-operations {
  margin-bottom: 15px;
}

.operation-hint {
  color: var(--info-color);
  font-size: 0.9em;
  margin-bottom: 10px;
}

.operation-hint i {
  margin-right: 5px;
}

.tree-list {
  user-select: none;
}

.category-item, .child-category, .grandchild-item {
  background-color: var(--background-color);
  border: 1px solid var(--border-color-light);
  border-radius: 6px;
  margin-bottom: 8px;
  padding: 10px 15px;
  transition: all 0.2s ease;
  font-size: 0.95em;
}

.category-item:hover, .child-category:hover, .grandchild-item:hover {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  border-color: var(--primary-color);
}

.category-header, .child-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
}

.category-main, .child-main, .grandchild-content {
  display: flex;
  align-items: center;
  flex-grow: 1;
}

.expand-icon {
  margin-right: 8px;
  transition: transform 0.2s ease;
  cursor: pointer;
  color: var(--info-color);
}

.expand-icon.expanded {
  transform: rotate(90deg);
}

.expand-placeholder {
  width: 22px;
  display: inline-block;
}

.category-name, .child-name, .grandchild-name {
  font-weight: bold;
  margin-right: 10px;
  color: var(--text-color);
}

.category-actions .el-button, .child-actions .el-button, .grandchild-actions .el-button {
  margin-left: 8px;
}

.category-children, .grandchild-list {
  margin-top: 8px;
  padding-left: 20px;
  border-left: 1px dashed var(--border-color);
}

.empty-state {
  text-align: center;
  padding: 50px;
  color: var(--text-color-secondary);
}

.empty-icon {
  font-size: 60px;
  color: #DCDFE6;
  margin-bottom: 20px;
}

.empty-state h3 {
  margin-bottom: 10px;
  color: var(--text-color);
}

.el-dialog__title {
  color: var(--primary-color);
  font-weight: bold;
}
.el-form-item__label {
  color: var(--text-color);
}
.performance-metrics {
  margin: 10px 0;
  padding: 10px;
  background: #f8f9fa;
  border-radius: 4px;
}

.performance-metrics h3 {
  margin: 0 0 10px 0;
  color: #409EFF;
}

.metric-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.metric-item .metric-label {
  color: #909399;
  font-size: 12px;
}

.metric-item .metric-value {
  color: #606266;
  font-weight: bold;
}
.academic-test-list {
  display: block;
  border: 1px dashed #ccc;
  padding: 10px;
  margin-top: 20px;
}
